Crank

ABSTRACT

A crank for a valve linkage system includes a pin sleeve having a bore for receiving a connecting pin to connect the crank to a link; a shaft sleeve having a bore for receiving a shaft; an arm between the pin bore and shaft sleeve; and a first stiffening rib extending from the shaft sleeve toward the pin bore.

BACKGROUND

The present invention relates to pneumatic air valves. In particular,the invention relates to actuator assemblies for pneumatic air valves.

Pneumatic air valves, sometimes called butterfly valves, in gas turbineengines typically include linkage systems. The actuator portion of thepneumatic air valve is cantilevered off the valve body to maintain alight-weight and simple construction. A linkage system is used totranslate axial motion in the piston into a rotation of a disk to openor close the valve.

Linkage systems in pneumatic air valves typically include two primaryparts: a crank and a link. The crank and link are pinned together with aclose-fit metallic pin. The crank can resemble a tuning fork likestructure with a sleeve and two extending arms to connect above andbelow a link.

SUMMARY

A crank for a valve linkage system includes a pin sleeve having a borefor receiving a connecting pin to connect the crank to a link; a shaftsleeve having a bore for receiving a shaft; an arm between the pin boreand shaft sleeve; and a first stiffening rib extending from the shaftsleeve toward the pin bore.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is perspective view of a pneumatic air valve.

FIG. 1B is a cross-sectional view of FIG. 1A.

FIG. 2A is a perspective view of a linkage system.

FIG. 2B is a perspective view of a crank in the linkage system of FIG.2A.

FIG. 2C is a cross-sectional view of the crank of FIG. 2B andconnections to the linkage system of FIG. 2A

FIG. 3 shows a block diagram of a method for installing a crank into apneumatic air valve.

DETAILED DESCRIPTION

FIGS. 1A and 1B illustrate a pneumatic air valve incorporating thepresent invention. Pneumatic air valve 10 includes actuator assembly 12and valve 14. Actuator assembly 12 includes linkage system 16, smallpiston 18, large piston 20 and actuator housing 22. Linkage system 16includes clevis 24, link 26, bolt 28, crank 30 and shaft 32. Valve 14includes disk 34.

Small piston 18 and large piston 20 connect to link 26 through clevis22. Link 26 connects to crank 30 through bolt 28. Crank 30 connects toshaft 32, and shaft 32 connects to disk 34 of valve 14.

Small piston 18 and large piston 20 move laterally based on a motor (notshown) controlling air in cylinders containing pistons 18, 20. Clevis 22translates that movement to lateral movement of link 26. The movement oflink 26 causes crank 30 to rotate, which causes shaft 32 to rotate. Therotation of shaft 32 causes disk 34 of valve 14 to open or close.

FIG. 2A is a perspective view of linkage system 16. FIG. 2B is aperspective view of crank 30 in linkage system 16, and FIG. 2C is across-sectional view of crank 30 and connections to linkage system 16.FIGS. 2A-2C include linkage system 16 with clevis 24, link 26, bolt 28,crank 30, shaft 32, spherical bushing 35 and washer 36. Link 26 includespin bore 37. While bushing 34 is shown as a spherical bushing, it couldbe other types of bushing depending on system requirements.

Crank 30 includes shaft sleeve 38 with bore 39, pin sleeve 40 with pinbore 41, arm 42, first stiffening rib 44 and second stiffening rib 46.Pin bore 41 can be a threaded bore to receive bolt 28. Crank 30 isgenerally one part, made of steel, aluminum, plastic or any othermaterial suitable for the situation. Crank 30 can be made by machining,molding, casting or other methods.

As mentioned above, to maintain a light weight system, actuator assembly12 of pneumatic air valve 10 is cantilevered off the valve body andconnected by linkage system 16. This arrangement makes actuator assembly12 susceptible to vibrations. Vibrations from valve 14 can be amplifiedwithin actuator assembly 12, causing galling in connections, especiallyat pin bore 41.

Past cranks resembled a “tuning fork” or clevis configuration with twoarms extending from a shaft sleeve with two separate pin bores on theends of the arms. A link with a pin bore would connect between the arms,with a pin inserted to hold the crank and link together. The “tuningfork” configuration has a low natural frequency which can excite in avibration environment. The vibrations in actuator assembly wereamplified in the low frequency “tuning fork” cranks, results in wear onthe connection between the link and crank.

Adding stiffening ribs 44, 46 increases the natural frequency of crank30, resulting in a more vibration tolerant crank 30 and overall linkagesystem 16. Ribs 44, 46 make crank 30 more rigid. This increase innatural frequency and rigidity of crank 30 through the design of asingle link 26 connection through pin bore 41 with arm 42 and ribs 44,46 makes crank 30 less susceptible to vibrations and vibrationamplification from valve body. This results in lower stress in crank 30and less wear and galling in linkage system 16.

Crank 30 can be connected to link system with an integral locking insert48. Integral locking insert 48 can be a helical wire insert into pinbore 41 in crank 30, with a part of the insert having a deformed thread.Integral locking insert 48 can act as a secondary means of retainingbolt 28 (primary retention means is torqueing bolt 28 into threaded pinbore 41) and making it very difficult to turn bolt 28 after it has runthrough the portion with the deformed thread.

FIG. 3 shows a block diagram of method 50 for inserting crank 30 intolinkage system 16 of pneumatic air valve 10. Method 40 includes steps ofaligning crank pin bore 41 with bore 37 in link 26 (step 52), insertingbushing 34 into link pin bore 37 (step 54); inserting and torqueing bolt28 to connect crank 30 to link 26 (step 56); and sliding crank shaftsleeve 34 bore 39 onto shaft 32 (step 58). Connection between crank 30and shaft 32 can be press-fit, splined or pinned depending on systemrequirements. While steps are shown in this order, they may be performedin a different order and may include interim steps depending on systemrequirements.

In summary, adding stiffening ribs 44, 46 to crank 30 and the design ofa single connection at pin bore 41 of crank 30 to link 26 makes crank 30more robust with increased natural frequency, allowing it to reducesusceptibility to vibration. The increase in natural frequency andreduced susceptibility to vibrations results in less wear on crank 30and overall linkage system 16, particularly in the connection betweenlink 26 and crank 30. This can improve life of linkage system 16 andoverall pneumatic air valve 10.

While crank 30 has been shown in the embodiments above to include ribs44, 46 above and below supporting member 42, it can have ribs only aboveor only below supporting member. The ribs can also take different shapesand/or sizes than those shown in FIGS. 2A-2C.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A crank for a valve linkage system, the crank comprising: a pinsleeve having a bore for receiving a connecting pin to connect the crankto a link in the valve linkage system; a shaft sleeve having a bore forreceiving a shaft; an arm between the pin bore and shaft sleeve; and afirst stiffening rib extending from the shaft sleeve toward the pinbore.
 2. The crank of claim 1, and further comprising: a secondstiffening rib extending from the shaft sleeve toward the pin bore. 3.The crank of claim 1, wherein the first stiffening rib is located abovethe arm and the second stiffening rib is located below the arm.
 4. Thecrank of claim 1, wherein the first stiffening rib is located above thearm.
 5. The crank of claim 1, and further comprising: an integrallocking insert inside the pin bore.
 6. The crank of claim 5, wherein theintegral locking insert comprises: a helical insert to hold a boltconnecting the crank to the link.
 7. A linkage system for connecting apneumatic actuation system to an air valve having a valve body connectedto a rotatable shaft, the linkage system comprising: a clevis forconnecting to the actuation system to be moved by the actuation system;a crank with a pin sleeve having a bore for receiving a connecting pin,a shaft sleeve having a bore for receiving the rotatable shaft, an armbetween the pin bore and shaft sleeve and a first stiffening ribextending from the shaft sleeve toward the pin bore; and a link with apin bore on one end for receiving the connecting pin and connecting tothe clevis on an opposite end to move with the clevis and to move thecrank.
 8. The linkage system of claim 7, wherein the connecting pin is abolt and the connection includes a bushing.
 9. The linkage system ofclaim 8, wherein the pin bore includes a helical locking insert.
 10. Thelinkage system of claim 7, wherein the crank further comprises a secondstiffening rib.
 11. The linkage system of claim 10, wherein the firststiffening rib is located above the arm and the second stiffening rib islocated below the arm.
 12. The linkage system of claim 7, wherein thefirst stiffening rib is located above the arm.
 13. A pneumatic air valvecomprising: a pneumatic actuation system; a rotatable shaft; a rotatablevalve body connected to the rotatable shaft; and a linkage systemconnecting the actuation system to the valve body, wherein the linkagesystem comprises a clevis for connecting to the actuation system to bemoved by the actuation system; a crank with a pin sleeve having a borefor receiving a connecting pin, a shaft sleeve having a bore forreceiving the rotatable shaft, an arm between the pin bore and shaftsleeve and a first stiffening rib extending from the shaft sleeve towardthe pin bore; and a link with a pin bore on one end for receiving theconnecting pin and connecting to the clevis on an opposite end to movewith the clevis and to move the crank.
 14. The valve of claim 13,wherein the connecting pin is a bolt.
 15. The valve of claim 14, whereinthe pin bore includes a helical locking insert.
 16. The valve of claim13, wherein the crank further comprises a second stiffening rib.
 17. Thevalve of claim 13, wherein the first stiffening rib is located above thearm and the second stiffening rib is located below the arm.
 18. Thevalve of claim 13, wherein the first stiffening rib is located above thearm.
 19. The valve of claim 13, wherein the actuation system comprises aplurality of pistons in cylinders controlled by a motor.
 20. The valveof claim 13, wherein the valve is a butterfly valve.
 21. A method ofinstalling a crank in a linkage system, the method comprising: aligningthe pin bores of a crank and a link, wherein the crank comprises a pinsleeve having a bore for receiving a connecting pin, a shaft sleevehaving a bore for receiving the rotatable shaft, an arm between the pinbore and shaft sleeve and a first stiffening rib extending from theshaft sleeve toward the pin bore; inserting bushing into the link pinbore; inserting and torqueing a bolt into the pin bores to connect thecrank to the link; and sliding the bore of the crank shaft sleeve onto arotatable shaft connected to a valve body.